Help! My Cat Is Constipated: Treating Constipation

Updated July 25, 2021

‘At A Glance (Details Below)’ Emergency Care

How To Treat Constipation In Cats

  1. See the vet as more than 50% of male cats who are thought to be constipated actually have a urinary obstruction.
  2. True constipation often has very few visible symptoms other than poor appetite and weight loss.
  3. Treatment is via dietary fibre, hyperosmotic laxatives, lubricants, diet & grooming.

Now dive deeper.

Later I’ll explain the diagnosis and treatment of constipation in cats. However, the greatest danger is to mistake constipation for urinary obstruction. That’s why I’ll start with Dante’s story.

The Constipated Cat Who Wasn’t

Dante is a middle-aged male cat who has always been healthy. One day, his owner noticed he was quieter than usual and not eating. He spent the day outside, was seen straining as if trying to poo, and when seen later was collapsed and panting.

She was sufficiently concerned to visit the emergency centre instead of waiting until the next morning to see us. Thank God she did.

Once he was assessed by the vet on duty, it was clear that his bladder was abnormally large, hard and painful. Blood was taken showing dangerous elevations in potassium, urea, and creatinine wastes normally excreted by the kidneys. A urinary obstruction was diagnosed and he was immediately admitted to relieve the blockage.

High blood potassium interferes with the function of the heart, and thus many obstructed cats die of cardiac arrest within hours. We can only imagine the excruciating pain they experience.

To continue the story, visit our page on prevention and treatment of urinary blockages in cats. From now on we’ll only discuss faecal problems.

Signs of Constipation in Cats

The signs of true constipation in cats can be:

  • Unproductive straining or pain on defaecation
  • Small, hard faeces sometimes with blood or mucus
  • Defaecation less than every day
  • Weight loss and poor appetite
  • Intermittent vomiting (read other causes of vomiting in cats here)
  • Lethargy

Most owners are unaware of the problem until it becomes severe and difficult to treat. However, there’s another way.

Diagnosis of Constipation

I diagnose most cats with constipation during a routine checkup. Vets can feel the abnormal accumulation of hard faecal pellets in the abdomen. If we suspect that your cat has just been lazy on that day we can always check again later. However, our first impressions are usually correct.

If the cat is large or difficult to palpate your vet will recommend an xray, which gives a quick and definitive answer. Although the cause of constipation is often not found, we observe that it is more common in older cats and certain breeds such as Burmese, Birman and Manx.

Treatment of Constipation in Cats

It’s vital to start treatment as soon as possible. The longer a cat’s colon is stretched, the weaker it gets, and the harder it is to return to normal.

Start with just one (I begin with lactulose) and gradually adjust doses or add other products. The whole time you need to monitor the consistency and frequency of your cat’s droppings.

Each product  shows a starting dose but  these usually need to be adjusted up or down (‘titrated’) to achieve an optimal result. I recommend a soft, formed stool not unlike dog faeces. Some cats will require a combination of treatments.

Diet Change

Mild cases may respond to a simple change from dry biscuits to a wet-only diet. This can also be better for your cat’s health; visit our page on carbohydrate content in cat foods for more information.

More difficult cases respond better to prescription diets that increase dietary fibre, such as Hills r/d and Hills w/d. Again, these are best used in their wet forms.

An increased water intake should also be encouraged to prevent faeces drying due to low water balance. Click here for advice on getting cats to drink more.


Paraffin-containing products can assist, but in my experience rarely work well on their own. There are several products that come in tube form, usually sold as a hairball treatment. For most owners, medical grade liquid paraffin is more effective.

Paraffin is extremely dangerous if given on its own, as cats can’t swallow it easily. This leads to aspiration pneumonia and death (I have seen this happen). Therefore, if using liquid paraffin, it needs to be mixed well into a wet food. Even then, risks are not eliminated.

Starting doses are usually ¼ to ½ a teaspoon twice a day in the food. It is said that regular use can deplete fat-soluble vitamins.

Hyperosmotic Laxatives

These in my experience are the most effective and best tolerated. They work by remaining intact in the colon, where they draw water into the faeces. The amount of water depends on the dose given.

My favourite is lactulose. A common Australian brand, Actilax, is pictured above. It is cheap and readily available at pharmacies. Once again, doses are usually ¼ to ½ a teaspoon twice a day in the food.

I have much less experience using propylene glycol but my reading suggests it is a more hazardous and less effective option.

Bulk Forming Laxatives

Soluble dietary fibre is well-known as an aid to regularity. It also works in cats, but the problem can be getting them to take it. Two such products are pictured above.

I recommend starting Metamucil or other unflavoured psyllium granules at the same doses of ¼ to ½ a teaspoon twice a day in the food. If cats refuse it, I then use Benefiber,  a wheat gluten product which is usually better tolerated. Start Benefiber at much lower doses of 1/16 teaspoon twice a day and increase to effect.

Both are best mixed in the food just before feeding to avoid them turning into gel too early. These products will produce a larger stool with an almost rubbery consistency if over-used.


We shouldn’t forget the effect that ingested hair can have, especially in longer-haired breeds like Ragdoll and Birman. These benefit from frequent brushing to remove dead hair, and in some cases, cats even need full body clipping twice a year.

Treatment of Severe Constipation

Many cats in the beginning, especially if the diagnosis is late, will need an enema performed under anaesthetic.  Sometimes it will need to be repeated intermittently even in well-managed cases. That’s why daily cleaning of the litter tray is almost essential as an early warning.

The late stage of chronic constipation in cats is called megacolon. Everything we’ve suggested so far is an effort to avoid this. While it can still respond to medical management, megacolon often needs to be surgically treated by removal of the colon.

Have something to add? Comments (if open) will appear within 24 hours.
By Andrew Spanner BVSc(Hons) MVetStud, a vet in Adelaide, Australia. Meet his team here. The information provided here is not intended to be used as a substitute for going to the vet. If your pet is unwell, please seek veterinary attention.

17 Replies to “Help! My Cat Is Constipated: Treating Constipation”

  1. Hi Andrew,

    I have read through this post after our appointment today. Thanks for all the info! Quick question – I have the Metamucil pictured and I have purchased Atilax. Until Piccolo’s next consultation, would you use solely one of these products or a mix of the two? I’m going to start with 1/2 teaspoon of Atilax twice a day with food as recommended. We won’t know if it’s working until our next visit so at some point should I add in Metamucil in addition to the Atilax twice a day?


  2. Interesting reading. Have just had my 17 yr old to the vets for constipation. Vet suggested 1ml of paraffin oil daily. Have used this with some effect, she did vomit large hair ball. So am presuming this is due to hair ingested.
    I have been using catlax, added fibre to diet, she eats raw, or tinned food. Minimal biscuits. She does appear much better, eating, drinking.
    I feel she has more to get rid off, she just hard, dry fur poo…had to help her get it off her butt.
    Thanks for the info.
    Regards Lynda.

  3. Thank you Dr Andrew for your very well written and very understandable explanation of treatment options for cat constipation. I have visited a local Vet five times in the last fortnight. I appreciate their expertise, but treatment options did not work.
    I’m an avid reader, so have turned to the internet looking for a knowledgeable website. Your’s was by far the best. I live in Melbourne so a visit to you is not possible. I will head off to the local chemist and get the lactulose pictured above. I am very careful with dosing (perhaps overly so, I have a touch of compulsive checking!) so will be very careful with my dear cat Minnie whom I love very much. As the saying in medicine goes, do no harm.
    If this doesn’t work out, I will seek another Vet or will have to make a sad choice for my elderly cat. I won’t wait till she is at a suffering stage. She presently eats and drinks, but no poo.
    No need for publication of my comments, but it’s totally up to you.
    Thank You Dr Andrew, you must be an all round lovely person, best wishes to you in all you do and wish for.
    From an elderly Glenda

    1. Thanks Glenda. Yes, it’s all about doing it very carefully. It’s also important that even if the treatment options from your vet have not worked, once you are using the lactulose that you go back regularly as I believe only a vet can really detect the level of constipation and tell you how things are going. Good luck.

      1. Thank you Dr Andrew. I was just re-reading your website today in case I missed something, and then I saw my comments, a lovely surprise. Yes I will continue to see a local Vet. I have an appointment with them next week. I told them I was managing well with the lactulose, and now stools were becoming frequent. I realise too Minnie had been more stressed than I thought from her Vet visits. She is a quiet, gentle cat and more home time has her eating and drinking water more. I shall keep vigilant in her care. I love her heaps. Many Thanks, Glenda

  4. Hi Andrew, thank you so much for this article. My two year old baby boy just got diagnosed with Intervertebral disc disease. I’m devastated.
    They caught it while doing an x-ray since he wasn’t feeling well. Thank goodness, but it also showed a backed up colon. They sent him home with wet food, fluids and pain meds and hope that helps him poop. But I want to try a laxative to help him feel better. What would you recommend? I live in the states.
    Please help.

    1. Hi Bella. You’ll find my advice for managing constipation in the text above. In addition to m that you will also need specific guidance from your vet.

  5. Hi!

    I have an elderly (19) cat (Egyptian Mau) with chronic constipation. He’s been diagnosed with megacolon and repeats this cycle for years: eats regularly (Royal Canin digestive fiber dry food) and the occasional packet of wet cat food designed for older cats, doesn’t poop at all for 2-4 days, then has an episode where he poops and vomits *everywhere* until it’s presumably all out.

    Recently, he’s also lost his appetite , lost weight, and become extremely lethargic. I took him into the vet the day after I noticed him straining to poop all day, followed by sleeping all day and turning down his wet food (which he never does). He also did not urinate that entire day. All of the signs appear to be constipation due to megacolon, but now I’m not so sure because he’s never acted this way before.

    Vet visit showed massive megacolon poop blockages on x-ray, but after reading several articles here I’m wondering if it’s a urinary blockage? They extracted some of the poop, but were unable to get to the higher blockage. As far as I know, he was not treated for anything urinary. He was given a sub-Q and some little, round, orange pills with no markings other than a divot down the middle (presumably an antibiotic?). When we got home he did finally urinate, but when he did it was a little in the litter box, then walking away, straining “to poop” and peeing in little puddle, like 7-8 of them, all over the kitchen floor. He’s done this for 2 days now. Still no poop.

    Blood test showed his WBC count was extremely high (234), PLT low (18.5), urea nitrogen high (43.4), sodium (157) and potassium (4.7) high, and something called “crawl” (?) (the Japanese is “Ku-roh-ru” (chlor? crawl? croru?)) also high at 121.

    The only environmental change is that my roommate of 12 years moved back to Australia, and she’s probably not coming back, so I don’t know what to do in terms of reducing stress. We try to spend quality time together but he seems to prefer hiding away these last few days. I don’t know what to do. I’m afraid the vet is not really doing much for him, but I don’t know if there is anything that can be done? It’s too expensive to keep going back if she’s not actually going to DO anything. Please help!

    1. Hi Sabrina. I would trust your vets’ opinion – megacolon is fairly obvious on x-ray and there’s no reason to imagine that there are two concurrent problems. My only advice is that if you are unsatisfied with the treatment so far, and you have already communicated this with your vet, then consider asking for a referral to a specialist. They may either suggest further medical therapy (likely to begin with) or suggest a surgical option. Good luck.

  6. Hi Andrew,

    I am having some trouble administering actilax solution to my cat who is a bit jumpy and anxious. Any tips? Most of the solution ends up on the floor or her fur.

  7. Hi Andrew, thanks for this info. My cat is 8 and has been repeatedly getting constipated over the last 6 months – episodes of strained and not producing anything but a few hard lumps. (not urinary problem, have made sure) I got him going consistently with Actilax but my current vet says she’s not sure about using it longterm as it’s a sugar so she has concerns about it possibly causing diabetes. Trouble is, everytime i take him off it, the constipation comes back. He’s on an all wet diet and i also add water to his bowl of food. The vet suggested adding psyllium, which i have done, but still – without the lactose he goes back to getting constipated. My vet thought that very odd when he’s on an all wet diet and has been for years now. Guess i am just looking for some other opinions about the longterm safety of lactulose. Thank you! Rachel

    1. Hi Rachel. It’s not at all odd for a cat to develop problems with constipation as they age. While I cannot vouch for the safety of lactulose, many vets have used it extensively without problems (including my own cat). Diabetes should not be a great concern given that it is indigestible (certainly not compared with the amount of carbohydrates in most cat foods!)

      1. Hi Andrew, thanks very much for your reply, most appreciated! That’s good to know because it’s the only way I have found to keep him regular and I only have him on a fairly low dose per day. He’s still getting sick though. Currently has pooh like water and recently had blood in it. Vet hasn’t done xray, said I could send him for ultrasound. She has suggested completely changing his diet but I am at a loss as to what to change it to as most cat food seems to be not so great for them, ironically?!

      2. Hi Rachel. Keep working with your vet and you should get to a better place. They can also help advise you on some good cat foods as it’s hard to get by without them.

  8. My vet suggested inulin- I have been giving 1/4 tsp twice daily in food with success – I dissolve it in a little water and mix it in meat, no issues of rejection, faeces improved from small hard pellets to more bulky soft stools. Bioglan make it with Jerusalem artichoke available from larger chemists.

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